\(\dfrac{5^x}{125}\)= 25\(^4\) b/
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18 tháng 7 2017

a,

\(\dfrac{5^x}{125}=5^4\\ 5^x:5^3=5^4\\ 5^x=5^4\cdot5^3\\ 5^x=5^7\\ \Rightarrow x=7\)

b,

\(\dfrac{3^x}{3}+3^{x-2}=4\\ 3^{x-1}+3^{x-2}=3^1+3^0\\ \Rightarrow x=2\)

c,

\(\left(x+\dfrac{2006}{2007}\right)^6=0\\ \Rightarrow x+\dfrac{2006}{2007}=0\\ x=0-\dfrac{2006}{2007}\\ x=\dfrac{-2006}{2007}\)

d,

\(\left(x-\dfrac{1}{5}\right)^3=\dfrac{8}{125}\\ \left(x-\dfrac{1}{5}\right)^3=\left(\dfrac{2}{5}\right)^3\\ \Rightarrow x-\dfrac{1}{5}=\dfrac{2}{5}\\ x=\dfrac{2}{5}+\dfrac{1}{5}\\ x=\dfrac{3}{5}\)

e,

\(3^x+3^{x-2}=810\\ 3^x\left(1+3^2\right)=810\\ 3^x\cdot10=810\\ 3^x=810:10\\ 3^x=81\\ 3^x=3^4\\ \Rightarrow x=4\)

g,

\(5^{x+2}+5^{x+1}+5^x=19375\\ 5^x\left(5^2+5+1\right)=19375\\ 5^x\cdot31=19375\\ 5^x=19375:31\\ 5^x=625\\ 5^x=5^4\\ \Rightarrow x=4\)

18 tháng 7 2017

cảm ơn nha bn. mk kết bn vs nhau nhé

19 tháng 11 2022

a: =>1/6x=-49/60

=>x=-49/60:1/6=-49/60*6=-49/10

b: =>3/2x-1/5=3/2 hoặc 3/2x-1/5=-3/2

=>x=17/15 hoặc x=-13/15

c: =>1,25-4/5x=-5

=>4/5x=1,25+5=6,25

=>x=125/16

d: =>2^x*17=544

=>2^x=32

=>x=5

i: =>1/3x-4=4/5 hoặc 1/3x-4=-4/5

=>1/3x=4,8 hoặc 1/3x=-0,8+4=3,2

=>x=14,4 hoặc x=9,6

j: =>(2x-1)(2x+1)=0

=>x=1/2 hoặc x=-1/2

5 tháng 8 2018

a. \(\dfrac{-39}{7}:x=26\)

x = \(\dfrac{-39}{7}:26\)

x = \(\dfrac{-3}{14}\)

b. \(x:\dfrac{13}{5}=\dfrac{7}{4}\)

x = \(\dfrac{7}{4}.\dfrac{13}{5}\)

x = \(\dfrac{91}{20}\)

c. x = \(\dfrac{-3}{5}-\dfrac{1}{2}\)

x = \(\dfrac{-11}{10}\)

d. \(x-\dfrac{3}{4}=\dfrac{9}{4}\)

x = \(\dfrac{9}{4}+\dfrac{3}{4}\)

x = 3

e. \(\dfrac{7}{8}:x=\dfrac{14}{3}\)

x = \(\dfrac{7}{8}:\dfrac{14}{3}\)

x = \(\dfrac{3}{16}\)

f. \(x:\dfrac{8}{3}=\dfrac{13}{3}\)

x = \(\dfrac{13}{3}.\dfrac{8}{3}\)

x = \(\dfrac{104}{9}\)

g. x = \(\dfrac{4}{10}-\dfrac{2}{5}\)

x = 0

chúc bạn học tốt banhquahahaleuleuok

11 tháng 9 2017

a/ \(x+\dfrac{3}{5}=\dfrac{4}{7}\)

\(x=\dfrac{4}{7}-\dfrac{3}{5}\)

\(x=-\dfrac{1}{35}\)

Vậy ....

b/ \(x-\dfrac{5}{6}=\dfrac{1}{6}\)

\(x=\dfrac{1}{6}+\dfrac{5}{6}\)

\(x=1\)

Vậy ....

c/\(-\dfrac{5}{7}-x=\dfrac{-9}{10}\)

\(x=\dfrac{-5}{7}-\dfrac{-9}{10}\)

\(x=\dfrac{13}{70}\)

Vậy .....

d/ \(\dfrac{5}{7}-x=10\)

\(x=\dfrac{5}{7}-10\)

\(x=\dfrac{-65}{7}\)

Vậy ...

11 tháng 9 2017

e/ \(x:\left(\dfrac{1}{9}-\dfrac{2}{5}\right)=\dfrac{-1}{2}\)

\(x:\dfrac{-13}{45}=\dfrac{-1}{2}\)

\(x=\dfrac{-1}{2}.\dfrac{-13}{45}\)

\(x=\dfrac{13}{90}\)

Vậy ....

f/ \(\left(\dfrac{-3}{5}+1,25\right)x=\dfrac{1}{3}\)

\(0,65.x=\dfrac{1}{3}\)

\(x=\dfrac{1}{3}:0,65\)

\(x=\dfrac{20}{39}\)

Vậy ....

g/ \(\dfrac{1}{3}x+\left(\dfrac{2}{3}-\dfrac{4}{9}\right)=\dfrac{-3}{4}\)

\(\dfrac{1}{3}x+\dfrac{2}{9}=\dfrac{-3}{4}\)

\(\Leftrightarrow\dfrac{1}{3}x=\dfrac{-35}{36}\)

\(\Leftrightarrow x=\dfrac{-35}{12}\)

Vậy ...

18 tháng 6 2018

Giải:

a) \(\dfrac{1}{3}x+\dfrac{1}{5}-\dfrac{1}{2}x=1\dfrac{1}{4}\)

\(\Leftrightarrow\dfrac{1}{5}-\dfrac{1}{6}x=\dfrac{5}{4}\)

\(\Leftrightarrow\dfrac{1}{6}x=\dfrac{-21}{20}\)

\(\Leftrightarrow x=\dfrac{-63}{10}\)

Vậy ...

b) \(\dfrac{3}{2}\left(x+\dfrac{1}{2}\right)-\dfrac{1}{8}x=\dfrac{1}{4}\)

\(\Leftrightarrow\dfrac{3}{2}x+\dfrac{3}{4}-\dfrac{1}{8}x=\dfrac{1}{4}\)

\(\Leftrightarrow\dfrac{11}{8}x=\dfrac{-1}{2}\)

\(\Leftrightarrow x=\dfrac{-4}{11}\)

Vậy ...

Các câu sau làm tương tự câu b)

a: \(\left|x\right|=3+\dfrac{1}{5}=\dfrac{16}{5}\)

mà x<0

nên x=-16/5

b: \(\left|x\right|=-2.1\)

nên \(x\in\varnothing\)

c: \(\left|x-3.5\right|=5\)

=>x-3,5=5 hoặc x-3,5=-5

=>x=8,5 hoặc x=-1,5

d: \(\left|x+\dfrac{3}{4}\right|-\dfrac{1}{2}=0\)

=>|x+3/4|=1/2

=>x+3/4=1/2 hoặc x+3/4=-1/2

=>x=-1/4 hoặc x=-5/4

26 tháng 7 2018

a) \(\dfrac{x}{48}=-\dfrac{4}{7}\Rightarrow x=-\dfrac{192}{7}\)

b) \(\left(x+\dfrac{4}{5}\right)-\dfrac{2}{5}=\dfrac{3}{5}\Rightarrow x+\dfrac{4}{5}=1\)

\(\Rightarrow x=\dfrac{1}{5}\)

c) \(2\left|x-1\right|^2=72\Rightarrow\left|x-1\right|^2=36\)

\(\Rightarrow\left|x-1\right|=6\)

TH1: x - 1 = -6 => x = -5

TH2: x - 1 = 6 => x = 7

e) \(\dfrac{x}{2,5}=\dfrac{4}{5}\Rightarrow x=2\)

f) | x - 2 | = 1 + 4 = 5

TH1: x - 2 = -5 => x = -3

TH2: x - 2 = 5 => x = 7

26 tháng 7 2018

a) \(\dfrac{x}{48}=\dfrac{-4}{7}\)

⇒ x.7=48.(-4)

7x = -192

x=\(\dfrac{-192}{7}\) Vậy x=\(\dfrac{-192}{7}\)

b) \(\left(x+\dfrac{4}{5}\right)-\dfrac{2}{5}=\dfrac{3}{5}\)

\(\left(x+\dfrac{4}{5}\right)=\dfrac{3}{5}+\dfrac{2}{5}\)

\(x+\dfrac{4}{5}=1\)

\(x=1-\dfrac{4}{5}\)

\(x=\dfrac{1}{5}\)

c) chưa từng gặp dạng với giá trị tuyệt đối sory

d) \(\dfrac{1}{6}x-\dfrac{2}{3}=2\)

\(\dfrac{1}{6}x=2+\dfrac{2}{3}\)

\(\dfrac{1}{6}x=\dfrac{8}{3}\)

\(x=\dfrac{8}{3}:\dfrac{1}{6}\)

\(x=16\)

e) \(\dfrac{x}{2,5}=\dfrac{4}{5}\)

=> x.5 = 4.2,5

5x=10

x=10:5

x=2

f) |x-2|-4=1

|x-2|=1+4

|x-2|=5

=>\(\left[{}\begin{matrix}x-2=5\\x-2=-5\end{matrix}\right.\) =>\(\left[{}\begin{matrix}x=5+2\\x=-5+2\end{matrix}\right.\) =>\(\left[{}\begin{matrix}x=7\\x=-3\end{matrix}\right.\)

đôi khi cũng có sai sót , hãy xem lại thật kĩ

3 tháng 8 2017

a) \(x+\dfrac{3}{10}=\dfrac{-2}{5}\)

\(x=\dfrac{-2}{5}-\dfrac{3}{10}\)

\(x=\dfrac{-7}{10}\)

b) \(x+\dfrac{5}{6}=\dfrac{2}{5}-\left(-\dfrac{2}{3}\right)\)

\(x+\dfrac{5}{6}=\dfrac{2}{5}+\dfrac{2}{3}\)

\(x+\dfrac{5}{6}=\dfrac{16}{15}\)

\(x=\dfrac{16}{15}-\dfrac{5}{6}\)

\(x=\dfrac{7}{30}\)

c) \(1\dfrac{2}{5}x+\dfrac{3}{7}=-\dfrac{4}{5}\)

\(\dfrac{7}{5}x+\dfrac{3}{7}=-\dfrac{4}{5}\)

\(\dfrac{7}{5}x=-\dfrac{4}{5}-\dfrac{3}{7}\)

\(\dfrac{7}{5}x=\dfrac{-43}{35}\)

\(\Rightarrow x=\dfrac{-43}{49}\)

d) \(\left[x+\dfrac{3}{4}\right]-\dfrac{1}{3}=0\)

\(\left[x+\dfrac{3}{4}\right]=0+\dfrac{1}{3}\)

\(\left[x+\dfrac{3}{4}\right]=\dfrac{1}{3}\)

\(x=\dfrac{1}{3}-\dfrac{3}{4}\)

\(x=\dfrac{-5}{12}\)

e) \(\left[x+\dfrac{4}{5}\right]-\left(-3,75\right)=-\left(-2,15\right)\)

\(\left[x+\dfrac{4}{5}\right]+3,75=2,15\)

\(x+\dfrac{4}{5}=2,15-3,75\)

\(x+\dfrac{4}{5}=-\dfrac{8}{5}\)

\(x=\dfrac{-8}{5}-\dfrac{4}{5}\)

\(x=\dfrac{-12}{5}\)

f) \(\left(x-2\right)^2=1\)

\(\Rightarrow x=1\)

Sức chịu đựng có giới hạn -.-

3 tháng 8 2017

- Mình tiếp tục cho Nguyễn Phương Trâm nhé.

g, \(\left(2x-1\right)^3=-27\)

\(\Rightarrow\left(2x-1\right)^3=\left(-3\right)^3\)

\(\Rightarrow2x-1=-3\)

\(\Rightarrow2x=-2\)

=> \(x=-1\)

- Vậy x = -1

h,\(\dfrac{x-1}{-15}=-\dfrac{60}{x-1}\)

\(\Rightarrow\left(x-1\right)^2=-60.\left(-15\right)\)

\(\Rightarrow\left(x-1\right)^2=900 \)

\(\Rightarrow\left(x-1\right)^2=30^2\Rightarrow x-1=30\)

=> x = 31

i,\(x:\left(\dfrac{-1}{2}\right)^3=\dfrac{-1}{2}\)

=> \(x:\left(-\dfrac{1}{8}\right)=-\dfrac{1}{2}\)

\(\Rightarrow x=\dfrac{1}{16}\)

- Vậy x=\(\dfrac{1}{16}\)

j, \(\left(\dfrac{3}{4}\right)^5.x=\left(\dfrac{3}{4}\right)^7\)

\(\Rightarrow \left(\dfrac{3}{4}\right).x=\left(\dfrac{3}{4}\right)^2\)

\(\Rightarrow x=\left(\dfrac{3}{4}\right)^2:\dfrac{3}{4}\)

\(\Rightarrow x=\dfrac{3}{4}\)

- Vạy x = \(\dfrac{3}{4}\)

k, \(8^x:2^x=4\Rightarrow\left(8:2\right)^x=4\)

=>\(4^x=4\)

=> x = 1

- Vậy x = 1

12 tháng 1 2018

2, \(\Rightarrow\left\{{}\begin{matrix}\\\dfrac{5}{4}x-\dfrac{7}{2}=0\\\dfrac{5}{8}x+\dfrac{3}{5}=0\\\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}x=\dfrac{14}{5}\\\\x=\dfrac{-24}{25}\\\end{matrix}\right.\)